I now come to those memorable weeks of November, 1921, which rank among the most important in American history. There was first the battle that had been preparing south of the Potomac between von Mackensen’s advancing battalions and General Wood’s valiant little army. This might be called the third battle of Bull Run, since it was fought near Manassas where Beauregard and Lee won their famous victories. Although General Wood’s forces numbered only 60,000 men, more than half of them militia, and although they were matched against an army of 150,000 Germans, the American commander had two points of advantage, his ten miles of entrenchments stretching from Remington to Warrenton along the steep slopes of the Blue Ridge mountains, and his untried but formidable preparations for dropping liquid chlorine from a fleet of aeroplanes upon an attacking army. In order to reach Washington the Germans must traverse the neck of land that lies between the mountains and the Potomac’s broad arms. Here clouds of greenish death from heaven might or might not overwhelm them. That was the question to be settled. It was a new experiment in warfare. I should explain that during previous months, thanks to the efficiency of the Committee of Twenty-one, great quantities of liquid chlorine had been manufactured at Niagara Falls, where the Niagara Alkali Company, the National Electrolytic Company, the Oldburg Electro-Chemical Company, the Castner Electrolytic Alkali Company, the Hooker Electro-Chemical Company and several others, working night and day and using 60,000 horsepower from the Niagara power plants and immense quantities of salt from the salt-beds in Western New York, had been able to produce 30,000 tons of liquid chlorine. And the Lackawanna Steel Company at Buffalo, in its immense tube plant, finished in 1920, had turned out half a million thin steel containers, torpedo-shaped, each holding 150 pounds of the deadly liquid. This was done under the supervision of a committee of leading chemists, including: Milton C. Whitaker, Arthur D. Little, Dr. L. H. Baekeland, Charles F. McKenna, John E. Temple and Dr. Henry Washington. And a fleet of military aeroplanes had been made ready at the immense Wright and Curtiss factories on Grand Island in the Niagara River and at the Packard, Sturtevant, Thomas and Gallaudet factories, where a force of 20,000 men had been working night and day for weeks under government supervision. There were a hundred huge tractors with double fuselage and a wing spread of 200 feet, driven by four 500 horse-power motors. Each one of these, besides its crew, could carry three tons of chlorine from Grand Island to Washington (their normal rate of flying was 120 miles an hour) in three hours against a moderate wind. I visited aviation centers where these machines were delivered for tests, and found the places swarming with armies of men training and inspecting and testing the aeroplanes.